1993 ford f-250 temperature mystery

So recently I got a ford f-250 because it rear ended a car and incurred minor radiator damage. So I replaced the radiator, temperature sensor, fluid, and burped the system. I dident replace the fan since it was still running strong and the water pump was pumping water through when I looked into the radiator. Now whenever I run it the guage shows the temperature rises untill about mid way then it stops for a while but after about a minute of throttle it continues to max temperature. Now theres no leakage whatsoever and the exhaust is clean so I dont think it's the gasket. Could it be the water pump has lost power or somthing with the wiring? At this point I'm stumped.

Thermostat?

Thermostat?

Replaced that to but to no avail